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Discussion Starter · #1 ·
I've noticed on a few occasions, while using the regen paddle on the steering wheel, the braking action has felt as if it wasn't engaging or was engaging to a lesser degree than normal. Just wondering if anyone else has experienced this or knows of an explanation for it.

Thanks!
 

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Was the battery almost full? Or were you on a rough road? Either one could cause this.
 

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Discussion Starter · #3 ·
Battery was probably half to maybe a third charged. Roads I travel are relatively smooth. Sometimes but not always, it is when I'm traveling at a higher rate of speed which I'm thinking just means that my speed is just too high for regen to slow it down?
 

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If battery full it will limit it to protect battery buffer. If over 70 mph I notice it does not engage right away. Maybe due to too much juice generated that would be going back to battery at that speed?


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Watch your kW meter on the right side of the DIC while using paddle. I notice it feels different from a deceleration G force from high speed than, say 35mph. If you see high kW, then it is working properly, regardless of your perception of rate of deceleration.
 

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Yes -- I have noticed this. At certain higher speeds, it actually seems to make no difference (I drive in LOW exclusively).

There is also an occasional "fade" sometimes at very low speeds where it seems to disengage for half a second and come back on.

One of the allures of the 2019 is that they claim to have tweaked the operation of the paddle and low to make it more smooth. I am definitely interested to see the changes as I don't think there is anything necessarily "wrong" with the paddle operation, it just needs some additional tweaks.
 

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In the Gen 2 owner manual section on Regen on Demand, the text says, "Regen on Demand allows increased deceleration by pressing and holding the steering wheel paddle. It works in D (Drive) and L (Low)...

...The accelerator pedal must be fully released for it to work..."

IOW, paddle won’t apply braking power in the Gen 2 until the foot’s off the accelerator...

The primary motor, MGB, creates the regen in both generations of Volts. In the Gen 1, your foot needs to be off the accelerator before regenerative braking can start, not simply "easing off," because you can’t use MGB as a motor and as a generator at the same time.

My understanding is that as you ease your foot off the accelerator under certain driving conditions in the Gen 2 Volt, the two planetary gear arrangement makes it possible for MGB to apply some negative torque (i.e., regen) as the car slows down. The effect of this would be to feel the amount of regen slowly "increase" as you eased off the pedal, and if you were then pulling on the paddle, the paddle regen would be applied at the moment your foot was completely off the pedal.

Perhaps this is an explanation for what you are experiencing.
 

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The primary motor, MGB, creates the regen in both generations of Volts. In the Gen 1, your foot needs to be off the accelerator before regenerative braking can start, not simply "easing off," because you can’t use MGB as a motor and as a generator at the same time.
It may be more complicated than that. And that certainly doesn't seem to be right for at least my car. On a nearby long downhill, I can maintain any speed I like (within limits) in just L with only the go-pedal. I couldn't do that if there was no regen at all until I completely released the pedal; the hill's steep enough (2.5%) to overcome rolling friction alone.
 

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It may be more complicated than that. And that certainly doesn't seem to be right for at least my car. On a nearby long downhill, I can maintain any speed I like (within limits) in just L with only the go-pedal. I couldn't do that if there was no regen at all until I completely released the pedal; the hill's steep enough (2.5%) to overcome rolling friction alone.
Are your sure? Seems to me that if my 2012 Volt were stopped at the top of a hill with a slope steep enough to overcome rolling resistance, if I were in Neutral when I took my foot off the brake, gravity would start pulling me down the hill, increasing my speed as time passed. If instead I was in D or L, the engineered "creep" would start the car rolling when I took my foot off the brake pedal, and then gravity would start pulling my car downhill (depending on how steep the hill was). I suppose I could then use the go-pedal to reach my chosen downhill speed (let’s say, 45 mph) faster than just letting the acceleration be provided by gravity.

Once the car is "coasting" downhill at the chosen speed, gravity continues to provide downhill force. If my Volt is in D, that mild level of regenerative braking counteracts the gravitational force, slowing any gravitational acceleration. If I shift from D into L, the increased regen may be sufficient to counteract gravity enough to maintain my chosen speed (no battery power being used). The ability of regen at either the D or the L level to maintain my downhill speed depends on how steep the road is.

L level regen might even be enough to overcome the gravitational pull and start slowing me down, requiring me to apply motor torque to maintain downhill speed.

Once I do step on the accelerator, regen stops, allowing gravity to once again join with the motor torque to increase my downhill speed until it reaches the chosen speed. When I reach the chosen speed, I ease up on the go-pedal until the motor stops applying torque, I start "coasting" again, regen kicks back in, and L regen slows me again until I drop below the chosen speed, when I then press down on the accelerator again and repeat the cycle...

Depending on the steepness of the descent, it doesn’t take much effort to modulate the pressure on the accelerator to apply motor torque as soon as the car starts to slow below the chosen speed and then stop applying it when the chosen speed has been reached... or I could set my Volt’s cruise control at 45 mph and let the car do the work.
 

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Once I do step on the accelerator, regen stops, allowing gravity to once again join with the motor torque to increase my downhill speed until it reaches the chosen speed. When I reach the chosen speed, I ease up on the go-pedal until the motor stops applying torque, I start "coasting" again, regen kicks back in, and L regen slows me again until I drop below the chosen speed, when I then press down on the accelerator again and repeat the cycle...

Depending on the steepness of the descent, it doesn’t take much effort to modulate the pressure on the accelerator to apply motor torque as soon as the car starts to slow below the chosen speed and then stop applying it when the chosen speed has been reached... or I could set my Volt’s cruise control at 45 mph and let the car do the work.
You are misreading what the car is doing. The regen is variable in L depending on position of the accelerator just like the regen of the brakes is variable depending on brake pedal pressure (up to maximum regen at which time the pads come in contact with the discs). That's why if you can feather the throttle to get the amount of regen you want. You aren't applying motor torque because the you are still applying regen to the battery. If the hill is constant you can position the throttle in such a position so the regen equals the pull of gravity and speed remains the same for the given throttle position. If the hill is variable you will have to vary the throttle to get the variable amount of regen to equal the variable amount of pull from gravity. If the hill to too steep the pull of gravity will exceed the regen and regen of brakes will be needed to maintain a speed.
 

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I know that the Gen 2 Volt can create regen while the other motor or engine is still applying torque to the wheels (i.e, while the foot is easing off the accelerator), but you seem to be saying the Gen 1, too, can do that. As your foot starts to apply light pressure to the accelerator pedal because regen from driving in L is slowing you down while coasting downhill, MGB continues to function as a generator, and the regen level is reduced (higher than D but lower than L), enabling you to balance regen against gravity, allowing you to maintain downhill speed.

Wouldn’t there be an issue, though, if you put just a bit too much pressure on your Gen 1's accelerator pedal, and the function of MGB is flipped from generator to motor, completely eliminating the regen braking? Once your motor is running, regen can’t be created until the motor function stops, allowing the generator function to start. That would seem to require reducing the pressure on the accelerator pedal to zero, not just easing off a bit like you can in a Gen 2. Of course, once down to zero, the generator function kicks in, and then you would regain the ability to reduce the rate of regen by applying light pressure to the accelerator, trying to avoid putting enough pressure on the accelerator pedal to reach the "switch from generator function to motor function" point.
 

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I have had my 2017 since early 2016. There were a lot of complaints on here about the paddle being too aggressive, jerky. That was my early experience too. But I got use to it and learned when to apply it. However. I have noticed it is not near as aggressive as it use to be now. Actually I wish it was about half as much again. I have to end up using the brake pedal a lot more now, where I didn't before coming to a stop. I don't know if the early feedback caused GM to make a software change at one of the services. I was planning to post on here and see if others had noticed this change when I found this thread. It was too jerky before, but now it seems way too soft. Wish this was a user setting for each driver style of driving. Or better yet, upgrade from on/off to progressive like the brake pedal.
 
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